Froling FHG-L 50 Install

[jebatty]

Excuse me if I drool a little, but you may too when you take a look at this install. The Froling will be heating a 6000 sq ft educational interpretive center at Deep Portage (DP) in north central Minnesota, an older building with poor to fair insulation, windows and doors. It will replace two LP hot air gas furnaces, which remain as backup units. It also will provide DHW.

The Froling was installed in its own boiler shed adjacent to the building, which also houses a 1600 gallon hot water storage tank. Domestic hot water is provided from a standard hot water heater which is now equipped with an integrated double wall heat exchanger and mixing valve. The tank can be heated to as high a temperature as the Froling will provide, and the hot water is mixed down to 120F for domestic service. With the 1600 gallon boiler hot water storage tank, there will be plenty of hot water, and DP also expects to be firing the Froling during the summer, perhaps once per week, to provide DHW.

This winter I should be able to do some temperature measuring and data logging and provide a performance report. And I am excitedly awaiting the opportunity to put the Froling through its paces. The installation finished yesterday. The Froling is operating, the system has being brought up to full temperature, and all components are in operation.

 

[Singed Eyebrows]

There's been a grievious error, this was installed at the wrong location, Milwaukee was the proper site. The Froling is nice & it looks like a very well thought out install, Randy

 

[Gasifier]

Jim,

Is that the extent of the insulation on that tank? It is going to be warm in that room to say the least. Nice set up. What does DP do again?

 

[EffectaBoilerUser (USA)]

This looks like a very nice installation.

I look forward to seeing some perfromance graphs of the Froling.

Was there any problem (with local officials) installing this as a pressurized system even though the boiler is not ASME rated?

Thanks,

Brian

 

[Gasifier]

Remembering that I am a newbie at these systems. What is that thing-a-ma-jig on the wall there in the last picture? And how does it work?

 

[ewdudley]

Remembering that I am a newbie at these systems. What is that thing-a-ma-jig on the wall there in the last picture? And how does it work?

Looks like a DHW flat plate heat exchanger. Maybe has integrated pump with variable speed to adjust flow from storage to meet demand, can't really tell. Integrated output mixing valve for anti-scalding.

http://www.heliodyne.com/products_systems/heating/shw_module.html

 

[jebatty]

ew has the link on the module. I didn't do this install and have not yet had a chance to explore the Froling, but very excited to do so.

Yes, more insulation will be needed, or otherwise this can be the staff sauna.

DP is an environmental learning center, serving children, families and adults; seminars, day camps, multi-day camps, etc., focusing on a wide range of environmental learning opportunities. Deep Portage

 

[jebatty]

I completed my second morning of operating the Froling. Although I have a penchant for hard data on everything, this report will be more experiential than data based. In short, this boiler is really "hot." It will take me more time to learn how to maximize the Froling, but that might not be necessary, as it appears to think quite smartly on its own.

Before my operations, staff at DP was experiencing some "slumber" (idle) operation, which the manual indicates should be avoided. The Froling is to be fired only when storage has capacity to absorb the entire wood load, assuming no system demand. My thought is that the slumber came from over-loading when storage would max out before the wood load burned out. Also, system demand was pretty low during these staff burns.

My initial loads both mornings were about 1/3 of the firebox, and adding some wood during mid-burns. The firebox is big compared to my Tarm. I had the boiler set at 80C maximum the first morning. The Froling does an excellent job of varying output based on boiler temp, which means that as boiler temp approached 80C the induced draft fan would slow down to lower the output, then speed up as temp dropped. Perhaps it "thinks" and puts together a demand scenario and modulates accordingly, but I don't know that. Operation was excellent, no slumber. I set 85C as boiler maximum this morning, and operation remained excellent, no slumber.

Clearly my initial loads could have been more than 1/3 full. System demand was higher these last two mornings than staff experienced days ago, with early morniong outdoor temps during my burns in the mid to high 20'sF.

Fire starts are effortless. The Garn has been the easiest boiler to start in my past experience (although I never would say that the Tarm is not easy), and the Froling has to be as easy as the Garn. Mid-burn reloads are effortless and smoke roll-out free. Open the outer door, the induced draft fan goes on "high," open the firebox door, add wood, close, fan slows down, and done.

I don't think it will take very long to learn how much wood to load based on remaining storage capacity, which the Froling tells you on its display panel. And I will add a variety of sensors when I have time and then I can a data based report, although it might be early winter before that will happen.

The DP goal is to eliminate use of its propane hot air furnaces by use of the Froling, as well as greatly reduce electric use for DHW. The ability to achieve this goal will be demonstrated as the heating season progresses. Propane remains available for backup or supplement, if needed.

 

[jebatty]

It's taken a long time to get to this update, and soon I hope to have hard data available. The install followed the plumbing Sketch A. 1) When the boiler is not operating, the load pulls from top of storage and returns cooler water to bottom of storage - operation as expected. 2) When the boiler is operating and no load, the boiler supplies top of storage and returns from cool water at bottom of storage - operation as expected. 3) But when the boiler was operating and there was a load, a major problem developed. Since all water leaving each of the tank and the boiler also must return to each, the result was that warm/hot load return water was being returned to the boiler and in this installation the result was boiler idling even though much cooler water was available from bottom of storage. If cool return water had been pulled from bottom of storage, the delta-T likely would have been sufficient to prevent or greatly reduce idling.

This problem also relates to the loading unit spec'd with the Froling and the demands of this particular system. The loading unit specs show maximum flow rate of about 12 gpm, but acutal flow rate is not known and based on the problem, actual flow rate is believed to be an unknown amount less than 12 gpm. The Froling output is rated at 170,000 btuh. Assuming actual flow rate of 12 gpm, at about delta-T >= 28, the maximum Froling output is handled by the loading unit (28 x 12 x 500 = 168,000). But at delta-T < 28, the Froling output exceeds the btu's that the loading unit can move. This normally may not not be an issue with some care in fueling the Froling, but in this particular install, due to warm/hot system return water to the Froling, delta-T appears to have been commonly less than 28F, and therefore idling was the result, even though storage had lower temperature water available to absorb the excess btu's.

The solution which was implemented last week is shown in Sketch B. This solution was possible because the 1650 storage tank had 3 extra 1" ports available. The boiler now supplies only to top of storage and the load draws only from top of storage. The return to the boiler now is only from bottom of storage (coolest water) and the return from the system via dip tubes now is to about the mid-point of storage (because system return still is warm/hot) to avoid mixing with the coolest storage water. Delta-T to the boiler now is at the maximum possible in this system.

Early indications are that a much improved system is the result. The Froling coasts easily to its set output of 80-85C, and decreases or increases the induced draft to maintain the optimum burn rate. With return water now from the bottom of storage, no idling is occurring. There still is more burn testing to be done, and I am data logging the following temps: boiler supply, boiler return, system supply, system return, and the tank with sensors near the top, at the middle and at the bottom of the tank.

 

[__dan]

Thank You for posting this. It is something I had been giving a lot of thought to.

In my own arrangement I wanted to prioritize cold start performance. With cold storage and the burner firing, heat to the load and not storage.

I was considering some way to have stratification and the weight of the tank water to work in auto, so when return comes back a lot warmer, the heavier colder water in the storage tank should now prioritize loading into storage. That would be the elegant solution. The brute force method would be to use electronic controls and pumps for loading and heat scavenging.

In diagram A, the return riser going up creates a heat trap (trapping the cold lower), so in reverse flow when the boiler is firing and loading the storage, the colder water has to first rise then fall into the boiler, prioritizing the other path, the warmer return water has the easier job of just falling into the boiler.

In my plan, the tank is tapped at the bottom, so the weight of the colder water pushes down and out to the boiler when the boiler is firing, tees right at the loading unit with the warmer return water, and ideally the primary secondary would mostly eliminate pumped pressure differentials between the tank and the boiler, so hot water would rise from the boiler to the header for availability to the loads, return water would mix at the loading unit and hopefully as the return got warmer the colder storage water would get increased priority from the weight of the colder water pushing down and out.

It's all theoretical now as the taps for it are in but the tank is not. And my priority is slightly different. Maximize cold start performance, ignore the storage until the return water comes back a lot warmer, satisfy demand with the least quantity of fuel and go back to ambient (restart cold), loading the excess to storage. With the boiler off, heat scavenging will be the priority.

Of course there's also a big difference running with 10 kw of load compared to 60 kw of load.

I thank you again because it's something that needs more thought, for standardized implementations to become routine. Returning of the warmer return water to the middle of the tank is a keen insight.

 

[ewdudley]

If return from system is warmer than bottom of storage, where did the cool water in bottom of storage come from?

It comes from system return after storage has been mixed by excess system flow after the end of the previous burn.

Another approach would be to control system flow such that system return is always at the minimum temperature consistent with satisfying load.

 

[jebatty]

Another approach would be to control system flow such that system return is always at the minimum temperature consistent with satisfying load.

This would be a very desirable result. A difficulty is dealing with an installed system and the expense of a change-over.

Later today I will post a graph showing the first data collection, and that will show system return temperature. The system drawing on the tank/Froling includes: 1) three zones supplied by a single 15-58 circ on Lo for two bedrooms plus a hallway; 2) two water to air coil units in the plenums of two LP furnaces (LP is “off”) each served by a separate 15-58 circ on Hi; and 3) a Heliodyne water/water hx unit served by a 15-58 on Lo to charge a dhw tank. The boiler loading unit is an LK 810 with an integral 15-58 circ on Hi. These all are as originally installed.
Any or all of these may have been active from time to time during the period that will be shown by the graph.

 

[jebatty]

The graphs show my first data collection since the plumbing change. I started the Froling with the first wood load at about 6:30 am and staff at DP tended the boiler thereafter. During the entire operation shown, the following demands would have been active according to calls for heat: 1) three zones supplied by a single circ for two bedrooms plus a hallway; 2) two water to air coil units in the plenums of two LP furnaces (LP is “off”); and 3) a heliodyne solar water/water hx unit to charge a dhw tank. Each is served by separate 15-58 circs, 1) and 3) on Lo and 2) on Hi (2 circs). The boiler loading unit is an LK 810 with an integral 15-58 circ on Hi. These all are as originally installed.

In my own arrangement I wanted to prioritize cold start performance. With cold storage and the burner firing, heat to the load and not storage.

The second graph shows that boiler supply to the top of the tank does not result in the same hot temperature water to system supply. While the temperature of the tank top rises rapidly, As does system supply temperature, the system supply temperature remains less than the boiler supply temperature. It is apparent that some mixing is resulting as hot water is supplied to the tank and as system return water is injected into the middle of the tank, and stratification, while good, likely could be improved by a different plumbing design.

I was considering some way to have stratification and the weight of the tank water to work in auto, so when return comes back a lot warmer, the heavier colder water in the storage tank should now prioritize loading into storage.

I’m not sure of the physics of your operational theory. Pressure is equal throughout the system. While stratification depends on density, I don’t think that somehow the weight of the water provides an “auto” operation, other than enhancing the stratification process.

In diagram A, the return riser going up creates a heat trap (trapping the cold lower), so in reverse flow when the boiler is firing and loading the storage, the colder water has to first rise then fall into the boiler, prioritizing the other path, the warmer return water has the easier job of just falling into the boiler.

For me this relates to the extent of mixing and impact on stratification during a load or discharge process.

Returning of the warmer return water to the middle of the tank is a keen insight.

Thank you, but there have been a number of posts dealing with improved methods of handling warm return water to maximize stratifcation and to make the hottest water always available to the system and the coldest water available to the boiler return to maximize delta-T and boiler hx performance. Ideally, warm system return water would be injected into the tank at various points, depending on the temperature of the return water and the temperature of the stratified tank water. Injection at a mid-point seemed to make the most sense in the DP application and multiple injection points involve more complicated controls and plumbing.

Some other initial observations, and analysis by others is welcome.

1) The first graph shows pretty good stratification occurring within the tank. The objective of making sure that coldest water was available to boiler return has been substantially achieved, while also achieving the objective of making hot water available to the system.

2) During the period of operation covered by the graph, outside temperatures ranged between about 28-40F. I know that the Froling was not being loaded with wood to achieve maximum output. My first wood load was about a 2/3 loading of the firebox, and I have good reason to assume that subsequent loading were likely to somewhat less than ½ of the firebox. Even with this loading the Froling easily handled all system demands and continued to charge the tank. The building being served is 6000 sq feet, 3 levels, and is a 1970's building, poorly insulated.

3) I’m not sure what is occurring during the two sharp downward spikes and quick recovery of the boiler supply temperatures. My initial thought is that some bridging might be occurring in the Froling burn process.

4) The graph does not provide data to indicate whether or not any idling occurred during the burn process. I was present during the first 1-2 hours of operation, boiler supply temperature was relatively constant, the induced draft fan was in continuous operation, was not noticeably modulating, and no idling was occurring during that time. At a later point I will add a sensor to monitor and log flue temperature, and that may provide more useful data to show the operational characteristics of the Froling, including idle periods which I think should be evidence by episodes of reduced flue temperature.

5) When weather gets much colder and the Froling can be pushed for maximum output over an extended period of time, I will do weighed wood burns and better assess the Froling performance.

6) The Froling is attended largely by inexperienced staff. I am working on wood loading instructions to make it easy for staff to not overload the Froling and cause idling when the tank does not have capacity to absorb the btu’s generated by the wood load. The Froling control has a sensor at about the tank mid-point which shows on the control display. Right now this will be used to indicate when and how much wood should be loaded.

7) I will be adding a display panel with digital panel meters to make it very easy to monitor various aspects of the Froling operation, much like I have done with the Wood Gun E500 and the Garn WHS3200 also in operation at DP and serving the main structures.

 

[__dan]

One thing everyone should really grasp is the awesome power available in an efficient clean burning system to raise 1000 gallons of water up in temp. Normally, 1000 gallons of water would just laugh at any attempt to raise its temp, like a flea biting a dog.

It's really a demonstration of the power of 90% efficient systems that can convert the available heat in cordwood into satisfying demand for large, usually immoveable loads.

I have burned four fires total since the beginning of October, just tempering the slab, and the house is running 69 in the morning, 72 in the afternoon. Have about two years worth of junk to burn in the yard until I really get into the seasoned oak splits. If I had to burn oil to heat the slab I would be waiting for Thanksgiving.

 

[BoilerMan]

One thing everyone should really grasp is the awesome power available in an efficient clean burning system to raise 1000 gallons of water up in temp. Normally, 1000 gallons of water would just laugh at any attempt to raise its temp, like a flea biting a dog.

It's really a demonstration of the power of 90% efficient systems that can convert the available heat in cordwood into satisfying demand for large, usually immoveable loads.

I have burned four fires total since the beginning of October, just tempering the slab, and the house is running 69 in the morning, 72 in the afternoon. Have about two years worth of junk to burn in the yard until I really get into the seasoned oak splits. If I had to burn oil to heat the slab I would be waiting for Thanksgiving.

I totally understand, but must disagree with this statement.

You can heat 1000 gal of storage with a 20% solid fueled boiler if you want to, just more wood! If you are not able to heat the same slab with oil you are undersized or over-pumped in the oil circuit.

Think about a typical statement: "That danged stove heats my shop better than my Miller trailer furnace". Well that stove is a tire-rim stove welded up with 6011 'farmer's rod' and he puts in a wheelbarrow full of wood twice a day. His Miller is rated at 60,000 btu.

Apples to apples says heat from any source at any efficiency will provide the same heat as long as the output is the same. Think about all of those OWB out there running less than 30% overall efficiency.

TS

 

[maple1]

I think you guys are saying the same thing:

More heat from less fuel.

 

[__dan]

Waiting for Thanksgiving means I am too cheap to pay for oil. Just google "cheap" and you'll see my picture. A winter with the slabs is ~ 1.5 tanks oil, maybe 450 gallons if I burned for heat the same way I burn wood. Since I was too cheap, I was burning one tank oil over the winter, 270 gallons. I have lots more heat now.

I'm burning branches, bark, and splitter debris right now, actually earlier today, the boiler is off and the house is 73.

Try raising the water temp on 1000 gallons of water by burning bark and splitter sweepings. The storage will just laugh. It's a big load to move around.

 

[Fred61]

cheap? Thrifty?

 

[jebatty]

From Sketch A it is apparent that the entire tank rather quickly will reach an equilibrium minimum temperature equal to system return temperature, and therefore, while the "coldest" water will remain at the bottom of the tank and be available to the boiler return, that "coldest" water will be quite warm and -T may end up in the vicinity of 20F +/-. At that temperature difference, and assuming 12 gpm from the loading unit, only 120,000 btuh can be moved from the boiler, which is well below the Froling capacity.

One solution to increase -T follows from ewdudley suggestion "to control system flow such that system return is always at the minimum temperature consistent with satisfying load." That I will have to work on. Initially two prime candidates are the 15-58's serving the 3 zones and serving the dhw hx.

Another solution would be to increase flow through the boiler to the tank, and a higher capacity circulator parallel to the loading unit would do this, and be controlled so that it would run only when tank return water was somewhat greater than 150F, for example. The loading unit's function to maintain boiler return water protection is not needed at this point, and I'm thinking that a relay to switch from the loading unit circulator to the parallel circulator, controlled by the Froling (the Froling would "see" the parallel circ as the loading unit circ), would do this.

Both of these fixes are only good so long as sufficient storage is available to absorb the excess btu's, and the Froling still cannot be loaded with wood when it's output exceeds system demand as the tank moves towards a full charge.

The Froling controls also have a way of dealing with this issue. The Froling modulates its output between 85,000 and 170,000 btuh. With the original design plumbing, this did not solve the idling issue, but a second issue was the Froling idling when the tank still had cold water available to store btu's. I think this may have mislead staff into believing that the Froling could still be loaded with wood because storage was not "hot."

Sketch A shows that the plumbing design changes will eliminate the "cold water available" issue and improve storage capacity, but idling to the extent caused by excess wood loading by staff still will need to be addressed. I think this can be adequately addressed once I add a monitoring panel that clearly shows the temperature of the storage tank and an instruction sheet is provided staff which will indicate how much wood to add based on storage tank temperature. This is the same procedure used for staff when loading the Wood Gun E500 and the Garn WHW3200, and wood over-loading is not an issue with those boilers.

 

[Chris Hoskin]

I'm really loving this thread, of course Jim, I wonder if you might want to get Fröling's "Vision" software that would allow you to easily monitor and data log most everything you are interested in and view it / save it onto an SD card or a laptop? Also, you may want to consider adding our Acaso Automix outdoor reset control. This time of year especially, you will just be sipping off the tank which will maintain better stratification and the lower return temps you are looking for. One last thing, I am reminded of Piker's install where he was seeing higher than expected/desired return temps - turns out the loading unit pump was moving water too QUICKLY. So what was happening was that a well defined stream developed in the tank where water was flowing from the supply straight to the return which was screwing up stratification and not doing much mixing either. I'm not sure that is what is going on here, but it might be worth trying turning the loading unit down a speed. Looking forward to hearing more. Chris

 

[jebatty]

Chris, thanks for the input, which I really appreciate. I will talk to DP about the software and outdoor reset, and I will try moving the loading unit circ from Hi to Med.

 

[TCaldwell]

Chris, does the software log combustion parameters such as 02, co2, co, flue temp and damper outputs? If so have you seen any data trends, or sold the software to anybody. It would be interesting to compare with the ones Brian Crawford posted for the effecta boiler.

 

[hiker88]

I suppose there must be some ghost in the machine factor for every install.

I had to put my circulator pump to high from medium because it was idling at lower than desired return temps. With the pump on high, and me weighing my wood before the burn, I can heat my 820 gallons of unpressurized storage 85c top, 80c bottom with zero slumber and a set point of 88c. With over 1100 hours on the unit now, only 21 hours has been in slumber.

I'm sure you will get it dialed in. I think the hardest part will be the number of different operators. Perhaps there will be a couple interested souls that will take the effort to load and run it properly.

Looking forward to the updates.

 

[Chris Hoskin]

hiker88 those stats are awesome! Well done.

 

[skfire]

I suppose there must be some ghost in the machine factor for every install.

I had to put my circulator pump to high from medium because it was idling at lower than desired return temps. With the pump on high, and me weighing my wood before the burn, I can heat my 820 gallons of unpressurized storage 85c top, 80c bottom with zero slumber and a set point of 88c. With over 1100 hours on the unit now, only 21 hours has been in slumber.

I'm sure you will get it dialed in. I think the hardest part will be the number of different operators. Perhaps there will be a couple interested souls that will take the effort to load and run it properly.

Looking forward to the updates.

Same here, setpoint 87, 845 gallons storage(total), cranking 85top, 80-82 bottom, no slumber with wood loads per volume,(eye balling it at this point)/outside temps/storage status/house temps, Logged in 1164 hrs, 13 hrs slumber. Pump is set at medium speed.

Right on about the operator fluctuations...when wife runs it, I make sure she underloads and get tanks to 85 top 50-60 bottom...playing it safe.

Just cranked it 3 days ago..all good.

Scott